Angiographic catheters are currently used in a variety of clinical procedures in which a fluid, particularly x-ray contrast media, is injected through the catheter into a blood vessel of the body leading to the heart, for use in flush studies and ventriculograms. To accomplish this, angiographic catheters are frequently threaded through the aorta and the heart itself to pass through a mitral valve for x-ray imaging of a heart ventricle or the like.
Many designs of angiographic catheters are known. However, typically, the currently preferred designs of angiographic catheters for flush studies or ventriculograms are so-called "pigtail" catheters, in which the distal tip of the catheter defines a loop, which facilitates the entry of the distal tip of the catheter through the mitral valve without causing any damage. Straight catheters are used for flush studies also.
Also, as shown for example in Ruiz U.S. Pat. No. 4,573,476, the distal end of an angiographic catheter may define side holes for the lateral outflow of x-ray contrast fluid or the like, along with a longitudinal distal exit for the catheter lumen, so that contrast fluid is also delivered out of the distal end of the catheter in longitudinal manner. The lumen of the catheter which is distal from the side holes may be of reduced diameter in order to direct a higher percentage of contrast fluid flow out of the lateral apertures, so that there is less direct forward flow of such fluid out of the distal tip.
Additionally, some commercially available pigtail-type angiographic catheters define a braided metal strand tubular reinforcing member positioned within the catheter wall along the majority of its length. However, this braided tubing is absent at the distal tip area where the side holes reside, and also in the pigtail area distal to the side holes.
Disadvantages have resulted in the manufacture of such catheters in that, while it is desirable to keep the catheter wall thickness to a minimum throughout its length, the braided metal strand reinforcing sleeve should be completely buried within the catheter wall and not exposed at either the inner or outer surfaces. Difficulties have arisen in keeping the braided metal sleeve so completely embedded, when a tubular distal tip is heat sealed to a separately formed portion of the catheter that carries the woven metal sleeve. Additionally, complaints have arisen in some currently available angiographic catheters of this type from surgeons who have reported that in clinical use, as they have attempted to put the pigtail tip through the mitral valve, the distal tip adjacent the junction between the tip and the rest of the catheter sometimes buckles. This is quite undesirable.
In accordance with this invention, an improved catheter is provided which may be used as an angiographic catheter, and which reduces or eliminates the manufacturing problem and the problem of clinical use described above. At the same time, the catheter can be made of a design which is otherwise substantially equivalent to the currently preferred angiographic catheters, to achieve the advantages that are presently obtained by such catheters, while avoiding the above-described limitations.